The Art of Reverse Tempering

GLOBAL economic growth—spurred
by the popularity of outsourcing
manufactured goods—continues its
unprecedented rise. During this period,
it’s interesting to note that much of the
offshore industrial windfall is focused
within warmer, often downright hot, climates.
Geographically warm areas in
Asia—China, for example—are struggling
to keep pace with a mushrooming
demand for lower-cost parts, components,
and finished products.

Likewise, new manufacturing processes
and advanced technologies often generate
significantly more process heat as they
operate. And if that’s not enough, the
growth in global dependence on Mideast
petroleum resources continues to stress
that industry’s facilities, which are obviously
in very warm climates. So a rapidly
growing number of offshore industrial and
commercial environments are dangerously
hot, due to either natural or man-made circumstances,
or both.

This places an ever-increasing population
of workers in a dangerous position:
Emergency response assets, including
drench showers and eyewashes, must not
only be made available, but these facilities
also require cooling of the water that flows
through them to avoid inflicting potentially
worse injuries on users.

Lest any reader think that this isn’t a
significant situation, consider your Saturday
car wash: When washing your car on
a hot summer day, the water can get mighty
hot if you let it stand in the hose for even a
short time. That’s because water is an ideal
transfer mechanism for heat. The sun heats
the outside of the hose and the water contained
in the hose absorbs that heat very
readily. You then turn on the hose to rinse
the car and get a surprise!

Now, consider the circumstance if
emergency shower feed water is left
standing in exposed piping, where either
high process temperatures or the sun can
significantly raise the temperature. If an
injured worker jumps under the shower or
forces his face into an eyewash stream
heated by the environment it is exposed to,
some dire results could easily follow.
Second and even third-degree burns are
easily possible. In fact, water at 100
degrees F is already sufficiently hot to
damage the delicate tissue of the eyes and
other areas of the body.

For many years, the operating water
temperature range of industrial emergency
drench showers and eyewashes was left
open to fluctuations, based on ambient
temperatures and other exposures. The
water that flowed through emergency
equipment was subject to climatic, source
affected, and other variables that could
raise it to dangerously high temperatures
or lower it to hypothermia-inducing cold
temperatures with no regulations or range
limitations. You pulled the handle, pushed
the flag, or rotated the foot treadle on your
emergency shower or eyewash, and you got
what you got. All of that changed with the
2004 revision of ANSI Z358.1.

Currently, OSHA in 29 CFR 1910.151
requires the availability of suitable first aid
treatment facilities. Direction is given
indicating that “suitable facilities for quick
drenching or flushing of the eyes and
body shall be provided. . . .” In the past,
the definition of “suitable” was generally
left to the specifier’s discretion. However,
ANSI Z358.1-2004 provides clarification,
and that clarification virtually eliminates
all ambiguity.

Sustained outlet temperatures, per the
standard, must be no lower than 60 degrees
F and below 100 degrees F during a full, 15-
minute use cycle for either an emergency
shower or an eyewash. Water that is colder
could lead to hypothermia, while hotter
temperatures can damage sensitive areas of
the body. Additionally, water at a higher
temperature that is applied to chemical splashes actually can intensify the injury.
In either case, the discomfort of the
victim can also lead to premature cessation
of the emergency equipment use.

The idea of an injured worker short-cutting
the required emergency equipment
use cycle because the water is too cold or
hot obviously led to the establishment of
the outlet water temperature range specified
by ANSI.

High Demand from Warm-Climate Plants
Recently, we have seen a dramatic increase
in the number of requests we receive for
Engineered Solutions dealing with cooling
emergency equipment feed water. In these
instances, radiant and ambient temperatures
in many areas within a warm-climate
plant often drive standing water temperatures
up above 120 degrees F. The
dynamics of heat transfer will raise the
standing water temperature at the emergency
equipment to dangerous levels
approaching the maximum ambient/
radiant air temperature.

When actuated, the emergency equipment would deliver very hot water to the
injury victim—exacerbating the injury, creating
more physical harm, or causing the
victim to recoil from the flow and cease the
drench or irrigation protocol.

With respect to cooling high-ambienttemperature
water to bring it within the
guidelines, the most popular approach is to
size a chiller and recirculation loop to
maintain the proper temperature at all
times for all equipment on the loop. A
variety of different products are available
based on the volume of water required at
peak demand and the footprint of the recirculation
loop specified. The accompanying
photo shows a large-capacity separate
chiller plumbed directly to an outdoor
enclosed emergency environment drench
shower booth.

This configuration can also be used to
allow the chiller to serve the needs of several
showers on a closed recirculation loop.
As is also the case with warming technologies,
all components must be matched to
ensure the availability of proper peak flow
rates and temperatures.

Emergency equipment manufacturers
are in the best position to assist with system
design because they know their equipment
flow rates, peak demands, and other associated
requirements.

A Step-by-Step Management Process
Just as progress has given us full function
emergency equipment and, later on, tepid
water requirements and solutions, it has
now also given us a clearly defined minimum
and maximum range of acceptable
outlet water temperatures. Designing and
managing an emergency equipment system
that is capable of delivering sustained use
volumes of properly tempered water
should be a step-by-step process.

It’s a matter of identifying your risks,
sizing your total system for peak flow use,
and factoring in local water conditions
(pressure and temperature), as well as seasonal
and process-related variations. Only
then is it possible to specify and match your
overall need to a tailored system, one that
is capable of delivering emergency equipment
water temperatures within the
required range. Even in international areas
that are not covered by ANSI’s standard,
the common-sense approach used in establishing
the Z358.1-2004 language should
be used as a guide for properly preparing
for the first aid needs of workers in any and
all environments.

This article originally appeared in the September 2007 issue of Occupational Health & Safety.

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